In paper handling machines, such as inserting machines, the use of an optical reading devices, for example, bar code readers, are well known. Generally, such optical readers are mounted in an appropriate location along the path in which the paper is conveyed for reading certain marks, for example, bar codes, that are preprinted on the sheets being conveyed. Typically, these marks are control marks which identify further processing to be performed downstream from the optical reader and which are situated at a fixed location on the sheets of a particular batch or "run" of material being processed.
It is known that an optical reader can be adjustably mounted along a paper path so that the reader can be positioned in a side-to-side or transverse direction to the paper path. In this manner, the optical reader can be positioned according to the location of the marks on the sheets being processed. It is common that an adjustment to the optical reader position is necessary when a new and different run of material is initiated, because the new run may contain control marks at a different location than the previous run, or the size of the sheets being processed may be different. Such adjustable mounting of an optical reader provides a capability to the paper handling machine for processing other runs of sheet material regardless of sheet size or location of the control marks. Typically, this type of adjustment is a course adjustment because the field of view of the optical readers do not require a delicate adjustment to read the control marks.
Presently, there is a need to read simultaneously multiple marks situated on a single sheet. The marks must be scanned as the sheet is fed from a sheet feeder. In one application, the marks represent control marks for at least two sheets which are initially printed as part of the single sheet being read and which are to be separated into two sheets when the single sheet is later split for further processing. The normal registration of the sheet being read does not ensure the simultaneous reading of multiple marks printed on the sheet. From one batch to another the location of the marks relative to one another may differ, for example, because one batch may have been printed on a different printer than the previous batch.
Although it is known to mount one optical reader on a mounting apparatus which allows for transversely adjusting the position of the reader over the location of the marks as the sheet is conveyed, such an arrangement does not provide a way to ensure that a plurality of readers are precisely positioned in a second direction to read a plurality of marks on a single sheet simultaneously. The typical mounting of optical readers provides only course adjustments which make it difficult to synchronize the reading of multiple optical readers. A fine adjustment of the relative positions of each reader is needed to synchronize the reading of the optical readers.
In U.S. Pat. No. 5,028,040 issued to Kalisiak on Jul. 2, 1991, there is shown an apparatus and method relating to registration marks applied to a form for insuring that the corresponding transversely adjacent form parts lie in length-wise registration with one another. In this patent, a pair of optical sensors are aligned with the path of travel of the registration marks on separated or overlapped form parts for detecting registration marks on each of the overlapped form parts. This patent does not show or suggest any device or method of adjustably positioning the optical readers for simultaneously reading control marks.